The appearances favour lymphoma with a differential including metastatic disease or primary sarcoma of the bone, although both are thought unlikely due to the preservation of the bony outlines.

Case Discussion

Histology

Microscopic Description

Sections show multiple small cores of highly cellular tumour with a significant degree of crush artefact. The cells appear to be a mixture of atypical cells with large pleomorphic nuclei as well as some chronic inflammatory cells. No specific architectural pattern is identified. Immunohistochemistry shows the majority of cells to express the B-cell marker CD20, while CD3 identifies a lesser population of small reactive appearing T lymphocytes. There is no staining for cytokeratin or S100 protein. The quality of the immunostaining for kappa and lambda light chains is poor however there is no obvious difference in the degree of positivity. MIB-1 demonstrates very high proliferative activity.